Method for the obtention of phenols from coal tars and lignite tars



Patented Oct. 8, 1935 PATENT OFFl CE METHOD FOR THE OBTENTION F PHENOLS FROM coAL TARS AND LIGNITE TARS Kurt Gieseler, Breslau, Germany, assi'g'r'uir to OberSchle'sischer Berg-11nd Hiittenmanmscher Verein e. V.,,Gleiwitz, Germany 1 No Drawing. Application July 22, I 1931, Serial No. 552,539. In Germany July 22, 1930 1 Claim.

Hitherto the coal tars and 'lignite tars and the products of distillation of the same have been obtained in that the oils are shaken with diluted alkalis, the alkaline aqueous phenolate solution 5 is separated, and from the same by means of acids especially carbon dioxide the phenols are separated again. The alkali, which has been used, is regenerated with caustic lime, this although it can be carried out increasing the'expenses.

Another method, in which the phenol-containing oils are treated with alcohol, obtains a good separation in lignite tars which contain up to 15% phenols, but is not applicable to tars with 25% and more phenol content as the alcohol then dissolves considerable quantities of hydro-carbons.

It has further been proposed to carry out the decomposition of the tars mentioned by means of sodium carbonate solution, ammonia Water, ammonia and alcohol, liquefied ammonia, alcohol and caustic soda, formic acid, petrol ethermethyl alcohol, sodium sulphide solution, superheated steam and other media.

Up to the present it has however not been possible, to effect on a large scale a complete separation of the hydrocarbons from the phenol by means of the proposed liquefied ammonia, which is a medium easily obtainable and .cheap, and which can also be easily recuperated. According to this known proposal, the liquefied ammonia has to act upon the tars during several days, when a stratum formation occurs. The mixture has then to be solidified at the temperatures of the liquid air, whereupon the upper stratum is caused to melt and separated from the still solid lower stratum. Neither enriching nor reduction of the phenols in the individual stratum has been thereby obtained.

According to the invention an almost complete separation of the tars into phenols and hydrocarbons can however be effected in that the tars or the distillates of the same are treated with the liquefied ammonia only during a short time, and the strata formed are separated in the liquid condition the one from the other by suitable devices, for instance after the manner of a separation funnel standing under pressure. The neutral constituents of the tars are, at suitable mixture proportions and temperatures, soluble only in small measure in liquefied ammonia, whereas the acid constituents are dissolved therein almost quantitatively. These acid constituents form with the liquefied ammonia a homogeneous stratum, which separates above the neutral oil, containing only little ammonia. Both strata can be easily separated in the liquid condition. After the ammonia has been driven out for recovery,

the crude phenols are obtained with a degree of purity upto Th'method may also be car- 5 ried out continually working.

As, especially in tar oils having a low boiling point, the crude phenol is obtained sometimes with only a low degree of purity, the method can be further developed in the following manner: 10

To the tar-ammonia mixture 3 to 10% of water or aqueous alcohol, such as methyl-alcohol or ethyl-alcohol or of any other organic solvent, such as acetone are added from the beginning. The solubility of the neutral oils in the ammonia- 5 phenol stratum is thereby reduced, and the yield in neutral oils as well as the purity degree of the crude phenol are increased. It is advisable to start from hydrated crude tars.

Example 1 20 A distillate from coal tar, boiling at from to 250 0., consisting of phenols 52%, bases 4% and neutral oil 44%, is treated with liquefied ammonia in being stirred at -50 C. Two strata 25 are formed instantaneously, the lower one of which being consistent and light colored, whereas. the upper film is dark colored. After the separating of the strata and the distilling off of the ammonia, the lower stratum consists of neutral 30 oil 99%, phenols 0.8% and traces of bases, whereas the upper stratum is composed of phenols 80.5%, bases 6% and neutral oil 13.5%.

Example 2 35 In a vessel under pressure a coal tar distillate possessing a boiling point above 250 0., consisting of 55% neutral, 41% acid and 4% basic constituents, is shaken with liquefied ammonia at +15 C. and allowed to settle. The lower stratum which is formed is withdrawn, liberated from the ammonia and consists then of 94% neutral, 2% basic and 4% acid constituents. The upper layer is composed of 83% acid, 11% neutral and 6% basic parts. 45

Example 3 A crude lignite or tar containing 86% of neutral, 1% basic and 13% acid constituents, is mixed in a vessel under pressure with liquefied am- 50 monia at 15 to 20 C. and the mixture allowed to settle. The lower stratum, 83% of the tar used still contains 1.2% phenols. The upper layer. after removing the ammonia contains 75% pure creosote. 55

Example 4 Example 5 The total distillate of the same tar is mixed with liquefied ammonia, and 3 to 10% methylalcohol of and allowed to settle to form layers. After separating the layers in liquid condition, the crude creosote has a degree of purity of 90%.

Example 6 The total distillate of the same tar is treated with liquefied ammonia and 3-10% ethyl-alcohol.

After separating the layers formed the crude creosote has a degree of purity of 90-95%.

Example 7 A crude lignite tar is mixed with liquefied ammonia with an admixture of 5 to 10% acetone in a suitable pressure vessel and allowed to settle to form layers. The separated upper layer contains 90% pure creosote after removing the ammonia.

Example 8 A crude coal low temperature tar containing 5% water is treated with liquefied ammonia with an admixture of 5 to 10% of a mixture of methyl alcohol and ethyl-alcohol and allowed to settle into layers. The separated crude creosote has a degree of purity of 90 to 95%.

I claim:-

Method for the obtention of high percent phenol products, containing to of phenol from raw coal tars and lignite coal tars by treating tars in any state with liquefied ammonia, separating after the stratum layer formation the strata in liquid condition the one from the other and removing the ammonia, consisting in adding to the tar-ammonia mixture up to 10% of water.

KURT GIESELER. 

